Process of making oleum.



I. J. 00X. PROCESS OF MAKING OLEUM. APPLICATION FILED 001?. 7, 1910.

1,002,824, Patented Sept. 12, 1911.

ITTORNEYQS.

To all whom 'it may concern:

UNITED STATES PATENT. OFFICE.

mvme J. coxjon no PONT, wA'snmG'roN, Assmnon TO E.'I. no PON'T mlNEMOUBS POWDER COMPANY, OF WILMINGTON, DELAWARE, A CORPORATION 01 NEW JEsEY.

PROCESS OF MAKING Application filed October"), 1910. semi No. 585,732.

Be it known that I, IRVING J. Cox, a citizen of the United States,residing at 'Du Pont, county of Pierce, and State of Washington, haveinvented a new and useful Improvement in Processes of Making Oleum,

of which the following is a full, clear, and

exact description, reference being had to the accompanying drawings,which form apart of this specification.

The object of my invention is to modify and improve a known process ofabsorbing sulfuric anhydrid in sulfuric acid for the purpose ofabsorbing a substantially greater proportion of SO in the gas, and ofobtaining fuming acid of a substantially higher degree of concentration,than has heretofore been possible.

It is well known that by bringing gas containing sulfuric anhydrid incontact with a: flowing body of sulfuric acid the latter will absorb acertain proportion of the sulfuric anhydrid, but it has been customaryto absorb the sulfuric anhydrid in a comparatively small volume of acid,and as the absorption evolves heat, the result has been that theincrease in temperature as well as the increase in concentration of theabsorption acid as it passes through the absorber is accompaniedby arapid diminution in the ability of the absorption acid to take thesulfuric anhydrid.

I have discovered that by reducing the temperature of the gas and of theabsorp-.

that has not heretofore been possible except to a very small percentageof the total output. In other words, both the absorption acid and thegas are used at atemperature that has been determined to be the mostsuitable for absorption, and the temperature increment as well as theconcentrationincrement are distributed over so large a volume of theabsorption acid that the acid remains continuously within thetemperature zone most favorable for absorption, and moreover, theconcentration of the absorption acid within the absorber is at-no timeappreciably higher than the concentration of the bulk of the circulatingacid. I

In carrying out my process I use an absorption tower, which may beempty, but which preferably contains .quai tz or other suitableacid-proof material in pieces over which the absorption acid flows inconsiderable wolume. From the absorption tower the ac1d flows by gravitythrough the coolerpreferably made ofa series of iron pipes and cooled bywater or air-and thence to a circulating tank provided with a pump forlifting the acid to the top of the absorption tower. The gas mayenterthe tower at the bottom and pass out at the top, or vice versa.Both gas and absorption acid are led lnto the tower at a temperaturebetween 85 and.115 F. and the ratio ofthe amount by weight of theabsorption acid to the amount by weight of the sulfuric anhydrid in thegas which passes the tower in a given time'is'not less than 43:1. Asabsorption acid I use acid from any convenient source, preferably thestrongest acid available in order that the desired maximum concentrationmay be the sooner reached; A charge of this acid is brought into thecirculating tank and then, by means of the pump above mentioned, iscirculated through the tower until the maximum concentration is reached.It is then removed from the circulating tank and replaced by 'a newcharge.

In the drawings, the figure is a diagram of an apparatus in which theprocess may be carried out.

a is the absorber containing quartz or other a'cid proof packing g.

b is the cooler through which the acid passes on the way to thecirculating tank 0.

d is the pump, by meansof which the acid is lifted, through the returnpipe line 6, to the top of the absorber, into which it is dis- .tributedby means of the distributer f.

h is the inlet for the gas and i the outlet. The apparatus described isold and well known as is also the process except that part thereofproviding for the described regulation of the temperatures and relativequantities of the'absorption acid and sulfuric anhydrid, upon whichnovel features depend theattainment of the objects of my inventionhereinbefore set forth.

By means of the process hereinbefore described, I succeed in turning outfuming acid containing as high as 45 per cent. free SO, and at thesametime' absorb an average of '60 percent. 'of the'total SO in the gas.This is accomplished in a single absorber.

specification ofLetters Patent, Pafented'sept, 12, 1911., i

Having now fully described my invention, I

I what I claim and desire to protect by Letters Patent is:

1.-The process of making oleum, which consists in causing sulfuricanhydrid at an initial temperature between 95 and 115 F.

to be brought into contact with a ,body of absorption acid at an initialtemperature between 95 and 115 F. in amount not less tween 95 and 115 F.to 'absorb sulfuric} anhydrid of a temperature within the same range,maintaining the ratio of the amount of absor tion acid to the amount ofsulfuric anhydri in the gas acted upon at not less than 43:1 by weight,cooling the concentrated; acid to a tem erature within said ra e, andrepeating t e cycle until the desire maximum concentration is reached.

I n testimony of which invention, I have hereunto set my hand at Tacoma,Wash, on this 28 day of'September, 1910.

- 0 IRVING J. COX. Witnesses:

Gms. S. LYONB, WALTER Gnms'mm.-

